The enjoyment and study of wild birds has been an enterprise of great numbers of enthusiasts for centuries. This perhaps is because wild birds are the most conspicuous and most readily observed form of wildlife. As written about 50 years ago:
Everyone is aware of them in the spring when their bright colors, lively movements, and chorus of song render them inescapable, but some birds are present at all seasons. Making the acquaintance of the common varieties in your neighborhood is an excellent way to establish a closer bond with nature. It will give you an understanding of that feel of kinship with the denizens of the wild, so characteristic of primitive peoples, and you will gain an awareness of the order in the world of living things and a perspective on human problems and concerns that are beyond price. It is no accident that so many of our great men have been keen students of wild birds. Few forms of outdoor recreation have so much to offer.
Audubon Bird Guide by Richard H. Pough, Doubleday & Company, Inc., 1946, Garden City, N.Y.
Extensive investigations of avifouna have been carried out over the years, for example by the Ornithology Laboratory of Cornell University. Such original research also has been buttressed by many birding enthusiasts whose sighting and presence reportings have contributed to more structured professional studies.
A popular technique, of course, for observing bird life is to visit their habitats while remaining inconspicuous. Since birds tend to return again and again to a given spot for food and water, a universally popular approach to observation has been to offer food and water at a more convenient location adjacent a home or the like. By selecting such food in consonance with the species desired to be observed, the observer may achieve a form of species specific selection of bird visitation. This may permit an easier access to species which are more rare, principally because of their territorial instincts. For example, in Eastern North America, a home based wild bird feeder typically will attract only one pair of titmice or nuthatches, and perhaps a small family of chickadees. That same feeding facility also may attract a dozen cardinals, many finches and doves, and substantial numbers of ecologically favored species such as sparrows. Unless some modicum of configurational aspect is included within a bird feeder design to supplant food based species selection, the station will be somewhat overwhelmed by the more popular species. For instance, a flock of sparrows may empty a feeder in short order, rendering it ineffective for its intended or preferred purpose.
The configuration of bird feeders also should look to the avoidance of non-avian animal life. Squirrels typically jump to an extent of about five feet vertically and may be airborne from trees and other structures horizontal distances up to about 12 feet. Should such non-avian wildlife succeed in invading the bird feeder, its feeding-attraction function will be halted and, in many cases, its structure damaged by animal chewing and the like.
Successful wild bird enjoyment also requires that the feeding station be maintained in a cleaned condition. For classic wooden feeders, this is a difficult task which is usually ignored. However, for active bird feeding stations, a cleaning of their structure typically is carried out by the serious bird enthusiast on an interval of about once per week.
Where practical cost constraints are ignored, presumably, bird feeders can be designed meeting the needs of species specific operation with enhanced food replenishment procedures. Additionally, such stations can, from time to time, be made invasion-proof to squirrels, black snakes, and the like, and may incorporate cleaning systems of elaborate design. However, for the typical consumer-bird enthusiast, such approaches are seen to be economically unattainable.